Acute Psychophysiological Responses to Cyclic Variation of Intermittent Hypoxic Exposure in Adults with Obesity

Hobbins, Liam, Olivier Girard, Nadia Gaoua, and Steve Hunter. Acute psychophysiological responses to cyclic variation of intermittent hypoxic exposure in adults with obesity. High Alt Med Biol 00:000-000, 2019. Background: We compared acute psychophysiological responses with a single intermittent hypoxic exposure (IHE)/normoxic exposure trial with varying cycle lengths in adults with obesity. Materials and Methods: Eight obese adults (body mass index = 33.0 ± 2.2 kg/m2) completed three 60-minute IHE trials (passive seating), separated by 7 days. Trials comprised 30-minute hypoxia/30-minute normoxia (inspired oxygen fraction = 12.0%/20.9%) over Short (15 × 2/2 minutes), Medium (10 × 3/3 minutes), and Long (5 × 6/6 minutes) hypoxic/normoxic cycles and a control trial (60-minute normoxia). Results: Arterial oxygen saturation was lower during hypoxic periods of Long versus Medium and Short trials (90.1% vs. 93.0% and 94.2%; p = 0.02 and p = 0.05), with no differences between Short and Medium. Prefrontal cortex oxygenation was lower (-5.1%) during all IHE interventions versus control (p < 0.02), independent of cycle length. Perceived breathlessness was unaffected during IHE but increased 15 minutes after exposure versus baseline (+34%; p = 0.04). Breathlessness was lowest after Short versus control from 15 to 60 minutes (-7%; p = 0.01). Conclusions: When implementing IHE, greater desaturation is observed during longer compared with shorter hypoxic/normoxic cycles in adults with obesity. However, IHE tends to be better tolerated perceptually with shorter rather than longer cycles. Final publication is available from Mary Ann Liebert, Inc., publishers http://dx.doi.org/10.1089/ham.2019.0002